IKA C 2000 control - Manual (Page 47)

IKA  -WERKE C 2000 basic / control Ver. 04 08.07
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The IKA  C 21 pelleting press, for example, is suitable for this purpose.
Most liquid substances can be weighed directly into the crucible. Liquid substances
exhibiting turbidity or containing water that will settle out must be dried or homoge-
nized before they are weighed in. The water content of these samples must be de-
termined.
Gelatin capsules or acetobutyrate capsules (see Accessories) that are filled with the
fuel sample are used with highly volatile substances. The gross calorific value of the
capsules must be known in order to take into consideration the combustion heat
generated by the capsules as extraneous energy.
The capsules described above or combustion bags made of polyethylene (see Ac-
cessories) are used for substances with low flammability or low calorific substances.
C 14 disposable crucibles can also be used.
Before the capsules or the combustion bag is filled with the substance to be deter-
mined, it must be weighed in order to determine the additional extraneous energy
introduced into the system from the weight and the gross calorific value (see the
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The amount of combustion aid should be as little as possible.
Almost all substances to be analyzed contain sulfur and nitrogen. Under the condi-
tions that prevail during calorimetric measurements, sulfur and nitrogen undergo
combustion and form SO
2
, SO
3
and NO
X
. Sulfuric and nitric acid arise in combina-
tion with the water resulting from combustion. Heat of solution is also generated.
This heat of solution is taken into consideration in calculating the gross calorific
value. In order to quantitatively record and determine all acids that have been
formed, about 5 ml of distilled water or another suitable substance can be added to
the decomposition vessel before the experiment.
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After combustion, the water that was added is collected and the decomposition ves-
sel is rinsed thoroughly with distilled water. The rinsing water and the solution
formed from the water that was added are combined and the acid content of the
combined solution is examined. If the sulfur content of the combustion aid and the
nitric acid correction are known, the water does not need to be analyzed.
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